From findagrave.com:

"Sidney Laurence Smith
LAURENCE SMITH DIES IN BATTLE
b. 1896, Canton, Illinois. He was attending a military school in Roswell, New Mexico when his parents moved to Aberdeen, South Dakota, ca 1915. He later came to Aberdeen and enrolled in the Northern Normal and Industrial Arts School where his father was head of the Art Dept.

When Co. L of the South Dakota National Guard was conducting the big campaign to bring it up to war strength, Laurence enlisted. Shortly afterwards this Co. went into camp at Mobridge(camp Pontis). Later some of its members were transferred to the 148th Machine Gun Battalion.

From this outfit Smith was later transferred to Co. L, 18th U.S. Infantry, 1st Div and saw some hot fighting in the Battle of Cantigny. He also saw active service at Montdidier, and was in the trenches there for 70 days. In Fosh's big drive, this company took part in the battle of Chateau-Thierry, and it was at Sessions, that Laurence met his death. He was a dispatch runner and it is known that he carried a message the morning of July 20. In some later activity of that day it is supposed he was killed. He had the rank of first class private.

Efforts of the Red Cross home service section were unavailing for months and months to obtain definite information as to the fate of young Smith. The aid of Congressman Royal C. Johnson was enlisted when he returned from France, and after nine months of uncertainty this information came to an end,the hope of the Smith family that more favorable word would come one day.

The telegram from the adjutant general's office at Washington, DC reads as follows:
"Pvt. Sidney L. Smith, Infantry previously reported severely wounded in action between July 18 and July 24, now reported Killed in action July 20." [1918]
The American Legion Post of Aberdeen, South Dakota, was named for Sidney L Smith."